[TUHS] Systematic approach to command-line interfaces

[Adam Thornton]

It's a measure of Unix having been wounded by its own success.

fork() is a great model for a single-threaded text processing pipeline to
do automated typesetting.  (More generally, anything that is a
straightforward composition of filter/transform stages.)  Which is, y'know,
what Unix is *for*.

It's not so great for a responsive GUI in front of a multi-function
interactive program.

These days, the vast majority of Unix applications are "stuff people play
with on their phones."

Adam

On Mon, Aug 2, 2021 at 7:59 AM Theodore Ts'o <tytso at mit.edu> wrote:

> On Sun, Aug 01, 2021 at 10:42:53PM -0400, Douglas McIlroy wrote:
> > > spawn() beats fork()[;] fork() should be deprecated
> >
> > Spawn is a further complication of exec, which tells what signals and
> > file descriptors to inherit in addition to what arguments and
> > environment variables to pass.
> >
> > Fork has a place. For example, Program 1 in
> > www.cs.dartmouth.edu/~doug/sieve/sieve.pdf forks like crazy and never
> > execs. To use spawn, the program would have to be split in three (or
> > be passed a switch setting).
> >
> > While you may dismiss Program 1 as merely a neat demo, the same idea
> > applies in parallelizing code for use in a multiprocessor world.
>
> It's certainly clear that some kind of primitive is needed to create
> new threads.  An open question is whether if there exists some kind of
> "new thread" primitve plus either spawn(2) or some kind of "create a
> child process and then then frob like crazy using 'echo XXX >
> /proc/<pid>/<magic files>'" whether there still is a need for a
> fork(2) system call.
>
> Obviously, as soon as we start going down this path, we're deviated
> quite strongly from the "radical simplicity" of Unix Version 7 that
> people have accused modern systems (whether they be Linux or FreeBSD)
> of lacking.  It's rather interesting that we haven't heard complaints
> about how people who dare to try come up with new API's are somehow
> traitors to "The Unix Philosphy" that we've seen on other threads.  :-)
>
>                                             - Ted
>
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